Head-up display (HUD) systems are of use in all types of vehicles, in particular automotive vehicles.
Head-up display systems display information projected onto a laminated glazing, which is reflected toward the driver or the observer. These systems make it possible in particular to give information to the driver of the vehicle without the driver looking away from the field of view forward of the vehicle, in order to guarantee that the driving is safe. The driver then perceives a virtual image which is located at a certain distance behind the windshield.
If a conventional laminated glazing is used for such a system, the driver observes a double image: a first image reflected by the surface of the windshield directed toward the inside of the passenger compartment and a second image reflected by the exterior surface of the windshield, these two images being slightly offset with respect to each other. This offsetting can disturb the viewing of the information. In order to overcome this problem, use may be made of a laminated windshield formed of two glass sheets and of an interlayer made of polyvinyl butyral (PVB), the two exterior faces of which are not parallel but wedge-shaped, so that the image projected by a display source and reflected by the face of the windshield directed toward the passenger compartment is virtually superimposed on the same image originating from the same source reflected by the face of the windshield oriented toward the outside. In order to produce this wedge-shaped laminated glazing, use is made of an interlayer sheet, the thickness which decreases from the upper edge of the glazing to the lower edge.